Preparation of diarylalkanes



- from the group consisting of hydrogen,

H 2,918,502 I Patented Dec.

2,918,502 PREPARATION DIARYLALKANES No Drawing. 'Application 1m 24, 1958 Serial No. 144,050 7 14 Claims. (Cl. 260-668) Thisapplication is a continuation-impart of my copending application Serial No. 594,083 filed June 27, 1956, now abandoned. This invention relates to a process for the preparation of diaryl compounds, and more particularly to a process for preparing diarylalkanes.

An object of this invention is to provide a process for preparing diaryl compounds.

Another object of this invention is to provide a process for the preparation of bis-diarylalkanes.

One embodiment of this invention resides in a processwhich comprises reacting a dialkyl substituted aromatic compound .of the general formula:

in which R, R R and R are independently selected alkyl, alkylene, cycloalkyl and cycloalkylalkyl radicals with a polyhaloalkene free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of aluminum chloride at condensation conditions, and recovering the resultant reaction products. A specific embodiment of the invention is found in a process which comprises reacting p-xylene with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of aluminum chloride at condensa tion conditions, and recovering the resultant reaction products.

A more specific embodiment of the invention resides in a process for the preparation. of bis-(p-xylyDmethane which comprisesreacting p-xylene with ethy'lidene-chlm ridein .the presencel'of aluminum chloride at a tempera United States v 2 ture in the range of from about 20 to about 150 C. and at a pressure in the range of from about atmospheric to about 50 atmospheres, and recovering the resultant bis-(p-xylyl)methane.

Other objects and embodiments referring toalternative dialkyl substituted aromatic compounds having the hereclopentylethyl)benzene, 1 methyl inbefore set forth general formula, alternative polyhaloalkanes and alternative catalysts will be found in the following further detailed description of the invention.

It has now been discovered that p-dialkyl aromatic compounds and more particularly, p-dialkylbenzenes, when reacted ,with a polyhaloalkane free of quaternary carbon atoms and containing at least two halogen atoms attached to the same carbon atom in the presence of certain Friedel- Crafts catalysts will form a dimerized p-dialkylbenzene, i.e., a compound containing two of the p-dialkylbenzene moieties. This reaction also is accompanied by several other reactions among which are alkylation, hydrogen transfer and transaralkylation to form other side prod ucts which may also be useful products. The thus formed dimerized dialkylbenzenes may be sulfonated and the resulting derivatives used as wetting agents. It is also possible to nitrate and reduce the products of the present invention to form monoand polyamines, these monoand polyamines being used to inhibit the oxidation of various organic compounds which are susceptible to oxidative deterioration. In addition the amines may in turn be converted to phenols by diazotization and hy drolysis to form other compounds which are also useful as oxidation inhibitors.

The reaction of this invention may be illustrated by the reaction of p-xylene with 1,1-dichloroethane, for example, as shown by the following equation:

A101: CHaCHCl:

1,4-dialkylbenzenes which may undergo reaction with the polyhaloalkane having the necessary configuration according to the process of this invention include 1,4- dimethylbenzene (p-xylene), 1-methyl-4-ethylbenzene, 1 methyl 4 propylbenzene, 1 methyl 4 isopropylbenzene (p-cymene), 1-methyl-4-butylbenzene, l-methyl- 4 isobutylbenzene, 1 methyl 4 amylbenzene, 1,4- diethylbenzene, 1-ethyl-4-propylbenzene, 1-ethyl-4-isopropylbenzene, 1-ethyl-4-isobutylbenzene, 1,4-dipropylbenzene, 1-propyl-4-butylbenzene, etc., l-methyl 4 cyclopentylbenzene, 1 methyl 4 cyclohexylbenzene, 1 ethyl 4 cyclopentylbenzene, 1 ethyl 4 cyclohexylbenzene, 1-propyl-4-cyclopentylbenzene, 1-propyl-4- cyclohexylbenzene, 1,4-dicyclopentylbenzene, 1,4-dicyclohexylbenzene, 1-cyclopentyl-4-cyclohexylbenzene, etc., 1 methyl 4 (cyclopentylmethyl)benzene, 1 methyl 4 (cyclohexylmethyl)benzene, 1 methyl 4 (2 cy ethyUbenzene, 1 ethyl 4 zene, l -ethyl-4-(eyclohexylmethyl)benzene,

hexylethyD-benzcne, 1 propyl 4 benzene, 1 propyl 1 propyl 4 (2 cyclopentylethyl)benzene, 1 propyl- 4 (2 cycloheigy'E; -(cyclopentylmethybbenef 1;-et hy1 4+;- (2 cyclopentylethyDbenzene, 1 ethyl 4" (2 :cyclo (cyclopehtylmethyl) '7 4. (cyclohexylmethybbenzene,

2H2-cyclohexylethyl)benzene, etc., l-methyl-4-(2 -ri1thylcyclopentyDbenzene, l methyl 4 (Z- ethylcyclolpentynbenzene, l methyl '4 (2 methyl'cyclohe'x'yl)- benzene, l-methyl-4-(2-ethylcyclohexyl)benzene, l-eth yl- '4 (2 methylcyclopcntyDbenzene', 1 ethyl 4 (2- ethylcyclopentyDbenzene, 1 ethyl 4 (2 methylgyclohexyhbenzene, l ethyl 4 (2 methylcyclohexyD- benzene, 1-ethyl-4-(2-ethylcyclohexyl)benzene, l-propyl4- KZ-methylcyclopentyDbenzene, l propyl-4-(2methylcyclohexyl)benzene, l propyl 4 (2-ethylcyclohexyl)benzene, .etc.

Polyhaloalkanes free from quaternary carbon atoms and containing at least two halogen atoms attached to the same carbon atom (the preferred halogens comprising-chlorine and bromine) whichmay be reacted with thej aforementioned dialkylbenzenes include dichloromethane (methylene chloride), chloroform, carbon tetra chloride, dibromomethane, bromoform, carbon tetrabromide, l,l-dichloroethane, l,1,2-trichloroethane l-,l-dibromoethane, 1,1,2-tribromoetha'ne, l,l-dichloroprdpane'-, 1-,-1-dibrornopropane, 2,2-dichloropr'opane, 2,2-dibro'mm propane, 1,1-dichlorobutane, 1,1-dibromobutahe, 2,2-dichlorobutane, 2,2-dibromobutane, l,1-dichloro-3-methylpropane, etc. The preferredpolyhaloalkanes are those in which the halogen is chlorine and/or bromine. It is understood that the above mentioned 1,4-dialkylbenzenes and dihaloalkanes free of quaternary carbon atoms and containing at least two halogen atoms attached to the same carbon atom are only representatives of the class of compounds which may be used, and that the process of this invention is not necessarily limited thereto.

The reaction between the l,4-dialkylbenzenes with a polyhaloalkane free of quaternary carbon atoms and con taining at least two halogen atoms attached to the same carbon atom takes place in the presence of certain active Friedel-Crafts type catalysts, said catalysts including in particular aluminum chloride, aluminum bromide, zirconium chloride and boron fluoride. The reaction will take place at temperatures ranging from about --20 to about 150 C. and preferably in the range of from about 0 to about 100 C., the range of temperature depending upon the reactors and the catalysts used. In addition, the pressure at which this reaction takes place should be sufiicient to maintain a substantial portion of the reactants in the liquid phase and may range from atmospheric to about 50 atmospheres or higher.

The reaction may be carried out, if so desired, in the presence of an organic solvent. However, the particular solvent used must be inert and should not enter into the reaction nor act as a hydrogen donor. Inert solvents which may be used include normal paratfins such as n-pentane, n-hexane, n-heptane, etc., cyclopentane, cycloliexane, etc.

The process of this invention may be effected in any suitable manner and may comprise either a batch or a continuous type operation. For example, when a batch -type operation is used, a quantity of the 1,4-dialkylbenzene and the catalyst are placed in an appropriate condensation apparatus and the polyhaloalkane free of quaternary carbon atoms and containing at least two halogen atoms attached to the same carbon atom dissolved in an additional amount of the 1,4-dialkylbenzene is gradually added thereto at the desired temperature. The reaction is often maintained in the range of from about 0 to about 25 C. During the initial portion of the reaction, the product may be raised to a higher tempe'rature and maintained thereat duringthe remainder of theresidence time. At the end of a predetermined time, the reaction product is separated from any unreacted starti-iig' material, washed with water and dilute alkali, dried and subjected to fractional distillation under reduced pressure to recover the desired product.

reaction between the 1,4-dia1kylbe'nzene and the polyhaloalkane having the necessary configuration ma also be eliectedin 'a continuous reaction; lri type of operation the -..-l,4 dialkylbenzene 1 is continuously charged to a reactor which is maintained at the proper operating conditions of temperature and pressure. The polyhaloalkane free of quaternary carbon atoms and containing at least two halogen atoms attached to the same carbon atom is also continuously charged to the reactor through a separate line or if so desired, the polyhaloalkane and the 1,4-dialkylbenzene may be adm1xed prior to admission into said reactor and charged thereto 1n a single line. A particularly suitable type of operation comprises a fixed bed type in which the catalyst is disposed as a fixed bed in the reactor and the reactants are passed therethrough either upwardly or downwardly. The reaction product is continuously withdrawn from the reactor, separated from the reactor efiiuent and purified by conventional means hereinbefore set forth while the unreacted starting materials may be recycled to form a portion of the feed stock. The reactants comprising the 1,4-dialkylbenzene and the polyhaloalkane are charged at a liquid hourly space velocity ranging from about 0.1 to about 10, said liquid hourly space velocity being defined as the volume of reactants per volume of catalyst per hour. i r

Other continuous types of operation which may be used in this process include the fluidized type of operation in which the reactants comprising the l,4-dialkylbenzene and the polyhaloalkane free of quaternary carbonatoms and containing at least two halogen atoms attached to the same carbon atom and the catalyst are maintained in a state of turbulence under hindered settling conditions in the reaction zone; the compact moving bed type of operation in which the catalyst and reactants are passe either concurrently or counterclirrently to each other; and the slurry type process in which the catalyst is car? ried into the reaction zone as a sln'rr'y in the l,4-dialkyl= benzene. It is to be understood that in each of the latter mentioned types of continuous processes tlie un reacted starting materials may be separated out and fe= cycled for use as a portion of the feed material while the desired product is withdrawn and purified.

The following examples are given to illustrate the process of this invention, which, however, are not intended to limit the generally broad scope of the present invention in strict accordance therewith.

Example I I A mixture of 2'12 g. (2.0 moles) of p-xylene' and 10" g. of aluminum chloride were placed in an alkylation flask. A solution of 98 g. (1.0 mole) of l,l-dichloroethane dissolved in 107 g. (1.0 mole) of p-xylene was slowly added during a period of about 1.7 hours while said mixture was being continuously stirred. The temperature of the flask was maintained at 22-26 C. during the addition. The reaction mixture was stirred for an additional 1.7 hours at a temperature in the range of from about 20 to about 26 C., during which time 7 g. of aluminum chloride was added at about 30 minute intervals in increinents of 3 g., 2 g., and 2 g. respectively. At the end of the reaction time the upper layer of the reaction mixture .was separated from the lower catalyst layer, washed with water, dilute alkali, dried and subjected to fractional distillation under reduced pressure. Thirty-two grams of bis-(p-xylyl)methane were separated from the reaction mixture.

There were also obtained cuts comprising 2-ethyl-pxylene (30 g.) boiling at 184 C. at atmospheric pressure) and 2,5-diethyl-p-xylene (4.5 g.) boiling at 225-230 C. at' atmospheric pressure).

Example -ll Ar'nixture' comprising 212 g. (10' moles) of p-x'yl'ene 10 6f chloride was placed in analky1at- 5 ing flask. While the miicture was continuously stirred 85 g. (1.0 mole) of methylene chloride dissolved in 107 g.

approximately one hour, during which time the temperature of the flask was maintained in the range of from 28 to 31 C. After completion of the aforementioned addition the reaction mixture was stirred for an additional two hours during which time the temperature of the flask was raised from 31 to 63 C. At the end of this time the flask and contents thereof were cooled to room tem perature and the upper layer separated from the lower catalyst layer, washed with water, dilute alkali, dried and subjected to fractional distillation under reduced pres-' sure. A.cut boilingat 134-l38 C, at 2.5 pressure (about 327-329? C. at 760mm. pressure) was separated. out. This cut, amounting to 18 g. and comprising bis- (p-xylyDmethane, crystallized upon standing and had a melting point of 62-63" C.

-In addition, there was also obtained 14 g. of a cut boiling at 111 C. comprising toluene, 24 g. of a cut having a boiling point of 167-169 C. at atmospheric pressure comprising 1,2,4-trimethylbenzene and 6 g. of a cut having a boiling point of 195-196 C. at atmospheric pressure and. melting at 78-79 C. comprising durene l,2,4,5-tetramethylbenzene) Example 111 flask and contents thereof are cooled to room temperature, the upper layer of the reaction mixture is separated from the lower catalyst layer, washed with water, dilute alkali, dried and subjected to fractional distillation under reduced pressure. The cut boiling at 158- 162 C. at 1.6 mm. pressure (about 357-363 C. at atmospheric pressure) comprising 3-(2-p-cymyl)-1,l,3,5- tetramethylindan, also named 3-carvacryl-l,1,3,5-tetramethylindan is recovered. This cut crystallizes and upon being recrystallized from ethanol has a melting point of l33-134 C.

In addition to the 3-carvacryl-1,1,3,5-tetramethylindan, toluene, isopropyl-p-cymene, 1,1,3,5-tetramethylindan, ethyltoluene, and ethyl-p-cymene are also recovered.

I claim as my invention:

1. A process which comprises reacting a dialkyl substituted aromatic compound of the general formula:

II R-C-R in which R, R R and R are independently selected from the group consisting of hydrogen, alkyl, alkylene, cycloalkyl and cycloalkylalkyl radicals with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of a Friedel-Crafts catalyst at a condensation temperature of from about --20 C. to about 150 C., and recovering the resultant reaction products.

' 1*.0imole)iofpexylene was gradually-added thereto. The "addition of the methylene chloride in'p-xylene consumed 2. A process which comprises reacting a diallti'ls ubq d m tiwqmmwm P esemi sjl tum t? in which R, R R and R are independently selected from the group consistingof hydrogen, alkyl, alkylene, cycloalkyl and cycloalkylalkyl radicals with a polyhaloalkane'free of quaternary, carbon atoms and'containing at least 2 halogen atoms attached to -thesarne carbon atomin the presence of aluminum chloride at 'a'.con-' densation temperature of;from.about"-20 C. to about C., and recovering the resultant reaction products. 3. A process which comprises reacting a dialkyl substituted aromatic compound of the general formula:

in which R, R R and R, are independently selected from the group consisting of hydrogen, alkyl, alkylene, cycloalkyl and cycloalkylalkyl radicals with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of zirconium chloride at a condensation temperature of from about -20 C. to about 150 C., and recovering the resultant reaction products.

5. A process which comprises reacting a dialkyl sub stituted aromatic compound of the general formula:

Rr-fl-Rs in which R, R R and R are independently selected from the group consisting of hydrogen, alkyl, alkylene, cycloalkyl and cycloalkylalkyl radicals with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of boron fluoride at a condensation temperature of from about -20 C. to about 150' C., and recovering the resultant reaction products.

6. Aproccss which comprisesreacting, p-xylene with a" polyhaloalkane" free of quaternary carbon; atoms 7 and i1 containing at least 2 halogen atoms attached to'the same carbon atom in the presence of. aluminum chloride at a condensation temperature of from about 20 C. to about 150 C., and recovering theresultant reaction products. 7. A process which comprises reacting p-cymene with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of aluminum chloride at a condensation temperature of from about 20 C. to about 150?. C., .and. recovering the resultant reaction products. .s 1 8. A process whichwomprises reactingzp-diethylbene zene. with a. polyhaloalkane free. of. quaternary carbon atoms and containing at. least 2 halogenatoms. attached to the same carbon atom in the presence ofaluminum chloride at a condensation temperature. of item about -20 C. to about 150 C., and recovering the resultant reaction products.

9. A process which comprises reacting p-dipropylbenzene with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of aluminum chloride at a condensation temperature of from about --20 C. to about 150 C.', and recovering the resultant reaction products.

10. A process which comprises reacting 1-ethyl4- propylbenzene with a polyhaloalkane free of quaternary carbon atoms and containing at least 2 halogen atoms attached to the same carbon atom in the presence of aluminum chloride at aicondensation temperature of from about -20'C. to about 150 C., and recovering; the resultant reaction products.v

11. A process for. the prepartion ot, bis'(prxylyl)methane which-.compriscslreacting s pjxylene with methylene" j I chloride in the perse'nce of aluminum chloride at a temperature in the-rangeofi from about 20 to about 150 C. and at a. pressure in the range of from about atmos- 4 ane which comprises reacting p-xylene with 1,1-dichloroethane in the presence of aluminum chloride at a temperature in the range of from about 20 to about 30 C. and at'a pressure in the range of from about atmospheric to about atmospheres, and recovering the resultant bis-(p-xylyDmethane.

13 A process for the preparation of bis-(p-xylyl)methane which comprises reacting p-xylene with 2,2-dichlorobutane in the presence'of aluminum chloride at a temperature in the range of from about -20to about 150 C. and at a pressure in the range of from about atmospheric to about 50 atmospheres, and recovering the resultant bis(p-xylyl)methane.

14. A process for the preparation of 3-carvacryl-1,1, 3,5-tetramethylindan which comprises reacting p-cymene with 1,1-dichl'o'roethane 'in' the presence of aluminum chloride at a temperature in the range of from about 30 to about C. and at a pressure in the range of from about atmospheric to about 50 atmospheres, and recovering the resultant 3-carvacryl-l,l,3,5-tetramethylindan.

References Cited in the file of this patent.

UNITED STATES PATENTS 2333331 Safier et al. .1; May 6,1958 

1. A PROCESS WHICH COMPRISE REACTING A DIALKYL SUBSTITUTED AROMATIC COMPOUND OF THE GENARAL FORMULA: 